Field of the invention
The present invention relates to hand railings constructed of metal tubes and more particularly to a railing system using prefabricated components.
At the present time it is known to form hand railings from metal tubes or pipes in a number of ways. The railing generally consists of a tandem series of evenly spaced posts which are vertically aligned. Each pair of posts is joined by one, two or more generally horizontally aligned rails. When the railing is used on the side of a stair, the generally horizontal rails are at an angle, for example, 35 degrees, from the true horizontal.
In one metal tube pipe system the ends of the horizontal rail tubes are externally threaded and screwed into a pip-threaded T on the vertical post. That system presents an inexpensive and unfinished pipe rail system which is unacceptable in quality building construction.
In an alternative metal pipe system the pipes are joined by external slip-on fittings available from Hollaender Manufacturing Company, Cincinnati, Ohio. That system also presents a railing having a crude appearance which is unacceptable in many locations.
In another system the tubular posts are formed with holes each having a round opening, with the holes being smaller in diameter than the post. For example, a 21/2-inch post (outer diameter "OD") has 2-inch hole (OD). Each horizontal rail ("side rail") is aligned with a hole and the end of the side rail is formed with top and bottom V-shaped cuts. The V of the horizontal (side) rail is placed next to the hole of the post. The post and rail are then welded together. The weld is then ground to present a smooth and finished joint. That system provides a strong railing which is architecturally acceptable due to its even finish. However, that system is relatively expensive since it involves considerable on-site skilled welding and grinding. In addition, the side rails are smaller in diameter than the posts.
In still another system the tubes are pre-finished and joined by a mechanical internal split-sleeve. The joints are adhered by epoxy adhesive and also by bolts. This "Connectorail" system (TM Julius Blum & Co., Carlstadt, N.J.), in one aspect, is shown in U.S. Pat. No. 4,150,907.